Starting and operating circuit for electric discharge devices



April 18, 1950 E. LEMMERS 2,504,548

- STARTING AND OPERATING CIRCUIT FOR ELECTRIC DISCHARGE DEVICES Filed Nov. 28, 1945 3 Sheets-Sheet 1 v Eg /0 gi m9 INVENTOR: EUG ENE LEM'MERS,

HIS ATTORNEY April 18, 1950 E. LEMMEZRS 2,504,548

STARTING AND OPERATING CIRCU FOR ELECTRIC DISCHARGE DEVICES Filed Nov. 28, 1945 3 Sheets-Sheet 2 FIG. 4 a

7 INVENTOR EUGENE LEMMERS,

7 HIS ATTORNEY April 18, 1950 E. LEMMERS ,5

STARTING AND OPERATING CIRCUIT FOR ELECTRIC DISCHARGE DEVICES Filed Nov. 28, 1945 3 Sheets-Sheet 3 FIG. 6 Q 2 /2&

INVENTOR: EUGENE LEMMER$ V I%B ATTORNEY Patented Apr. 18, 1950 UNITED TATES PATENT 2,504,548

STARTING AND QPERA'iiNG cmoui'r FOR" ELECTRIC DISCHARGE DEVICES Eugene Lemma-s, .Clevelancl assji'gr'i'or t'oiGeneral Electric Company, a corpora- Application ovember 28 1945 Serial hlo. 3 Claims: (Cl. 315 254) My invention relates genera-1y to gaseous electr'lc discharge devices; and more particularly to starting" and operatingcircuits therefor.

object of my invention is to provide ci-r' c'uits' for startinggaseous electric discharge devices, particularly lamps, such-as the k-nown com meter-any available fluorescent lamps, by means of which the lamps will be started practically instaritaneously andwill operatewith comparatively 16w powercon'sumption in the ballast. Another object is to provide such an arrangement memes supplementary means are provided to heat the electrodes during starting, and then thesupplementary heating means is reduced? or neutranzea when the lamp starts, without the use of moving parts such as switches.

In one type of circuit now in Wide use with fluorescent-lamps, the lamp isconnect ed across a' sour'ce of power in series with a reactorfl or choke coil, and. the acti'va-ted-filamentary elec-' trodes of-the lamp are temporarily short circuited liy a suitable switch to connect them in series across the power source and thereby cause then-i to be preheated-to anelectron emitting ternperature; Upon opening the switch, an induc'tive' kick oi 'surgefrom the'choke coil efie'cts starting of adischarge in the lamp. Such circuits provide r'eliablestarting, operate at good efiicie'n cies, and make for-long lifeof the lamp electrodes. However; disadvantages are the need for a switch which must be carefully designed and must he replaced periodically, and the" relatively slow starting occasioned by the preheating period.

In another type of circuit arrangement, re'-' ferried to as the so-called instant start type, switches are' dispensed'with and thelam'p started by connecting it across the terminals of a transformer capable of supplying a potential suffi c'i'eiitlyhigh tdbre'ak down the gaseous column between the electrodes and start a discharge therebetween. Howeverysince the lamp operates at'a voltage much lower than" that necessary to start it, the transformer unavoidably operates with a relatively high power loss. The starting withoutpre-heating of the activated electrodes is also hard on the electrodes.

According to the present invention, an arrangement is provided having advantages of both types of arrangements referred to above, but eliminating the disadvantages. Thus, the lamps start substantially instantaneously without undue sputtering of the electrodes and with relatively low power loss in the ballast.

Further features and advantagesof my invem tion will appear from the "following description of'speci'es thereof.

Fig. 1 is a'diagrammatic'view of an electric discharge device and a startingand operating circuittherefor incorporating my invention.

Fig. 2'i1lustrates the invention in a two-lamp circuit.--

Figs. 3 to-6 illustrate modifications of the'start ing arrangement of Figs. 1 and 2.

Referrin' fiQFig. 1, the disohargedevi'ce 1 shown "herein may be an ordinary fluorescent lamp of the positivecolumn electric discharge typelcomprising a? tubular envelope; with thermionic electrodes s nat, preferably athe form of coiled coilof tungsten; wire activated with'th'' uses mixture of barium andstrontium oxides, If desired, the electrodes 3, 3 may be proportioned so that the-voltage drop across each of them witha current sufiicient to" bring it to electron-emit ting temperature is slightly greater than the resonance] or ionization voltage of the gas or vapor in the lamp, whereby a local arc discharge is formed across the ends" of the electrode; The envelope: of the lamp conta'ins a gas; such as argon, at a" pressure" of a few millimeters and a small quantity of mercury which, during operation of the lamp, has a low pressure of the order of ten microns, and the'side walls'of the envelope have a phosphor coating thereon which when excitedby a discharge through the mercury vapor produces fluorescence.

The lampis connected across a suitable source of potential, preferably a voltage step-up auto transformer 5, and in series with a current limit ing inductance or choke coil 6. The auto trans-j former'in turn is connected across a source of power 1 which, for example, maybe a 115 10113; cycle supply.

In-accordancdwith my invention; I provide windings Sand 9jon' the" core of the auto trans'fl former 5 and inductively coupled therewith, and I also provide windings l0 and]! on the core of the choke coil 6 and inductively coupled therewith. The filamentary electrodes, in this case; are each connected in series with a winding of the; supply transformer wand a winding of the choke coil. Thus electrode 3 is" connectedi ri serieswith inductively coupled auto transformer coil 8 and in series with inductively' couple d choke coil Ijl. However, the coils" 8 and Hi are connected d opposite electromotive forcetoeach' other, i. e., in bucking relationship;

Fila;

mentaryelectrode l' connefcted series with coilsj 9 and It and filamentary electrode 3 connected" in series with c0ils8arid ll comprise the start ing and electrode heating circuits I2 and i=3, re spectively.

It isprf'erable tdconnect" the inductively pl'ed nansrormerpoiis a ands insuch a. mans i that their voltages are in phase with and add to "thevoltage across the'auto trarisfOri-her" 51 a when thepo'wer supply is turned on, coils 3' and El inductivelyenumeratetheauto=t1ansrorliiei* 5 areen'ergiz'ed' and thus cathode heat}; enough" for electron emission, and potential for starting issupp'lied'to filamentaryelectrodese anddi As soon as the discharge occurs between" the" his-f mentary' electrodes 3 and l and current flows through-the choke coil 6 the 'EiM'. Fxofthecoils supplying cathode heat; namely a 'and Si, is'op-' posedby theinduced E; M. F. or bucking effect in coil it! and II respectively. The cathode heat 3 power is thus automatically turned off. Perfect opposition between the coils is not necessary for the successful operation of the circuit. In fact, a small amount of additional cathode heat is sometimes desirable during operation of the arc discharge to lower cathode potential drop.

The presence of electrode heating windings 8 and 9 makes it possible to use a transformer having a lower Open circuit voltage than would otherwise be necessary to start the lamp l. However, those windings would entail a power consumption which is not necessary during operation of the lamp since the electrodes are then kept heated by the discharge. Such power consumption is eliminated by the bucking windings i9 and II.

It is possible that the heating of one of the electrodes may be dispensed with. In that event, one heating winding and its cooperating bucking winding may be eliminated. Thus, for instance, the windings 9 and it may be omitted. In that event, the electrode 3 may be short-circuited, if

desired, by connecting its terminals or leads together outside the lamp.

Fig. 2 incorporates Fig. 1 in a two-lamp circuit. The lead circuit, at the left, embodies corresponding parts of the lag circuit except for the addition of the capacitor 14. The corresponding parts of the lead circuit are designated with the same numbers primed.

Fig. 3 incorporates the same above-described corresponding parts of Fig. 1 and Fig. 2 for the lead, circuit but embodies voltage step-down transformers l5 and IE to which are inductively coupled the coils l9 and H, and coils 3 and 9' respectively. This arrangement reduces the wave distortion due primarily to the capacitor 4 and the combination of the choke 9 and auto transformer 5 usually sharing some iron in their magnetic circuits. During operation of the lamp, the primary of transformer It draws very little current.

-The arrangement of the step-down transformer 16 as shown in Fig. 3 may be used in those cases where the lamp i has a break down voltage lower than the voltage of the line or power source 1', in which case the step-up transformer 5 is eliminated.

Fig. 4 incorporates the same above described corresponding parts of Fig. 1 except that in the filament heating circuit I 3 a section I8 01 the choke coil 6 is used as a bucking winding instead of the coil H of Fig. 1. Also, a section ll of the transformer 5 is used as the heating winding in heating circuit 12 instead of the winding 9 of Fig. 1. In other words, the windings l1 and iii are in this case directly coupled to the transformer 5 and choke coil 6, instead of being inductively coupled as are the windings 9 and H in Fig. 1.

The circuit of Fig. 5 is similar to that of Fig. 2 except that the bucking eiIect for the heating circuit of a given lamp is obtained from the operating circuit of the other lamp. Thus, in the heating circuits i2 and i 3 for lamp I, the heating windings 9 and 8 are connected to the bucking windings I i and I9, respectively, which are coupled to the choke coil 9' in the operating circuit of the lamp 1'. Similarly, the heating windings 8' and 9 for lamp I are connected to bucking coils Ill and H which are coupled to the choke coil 9 in the operating circuit of lamp 1. This arrangement can result in still lower wattage loss per lamp than the Fig. 2 arrangement.

Fig. 6 incorporates the same above described corresponding parts of Fig. 1 except that coils 8 and I I are connected in parallel with each other and with filamentary electrode 3, and coils 9 and it are also connected in parallel with each other and with filamentary electrode 4, thus comprising heating circuits [3 and I2 respectively.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In combination, a source of current, a gaseous electric discharge device having at least one thermionic electrode and a cooperating electrode, an autotransiormer, an inductive ballast, a voltage step-down transformer inductively isolated from said autotransiormer and said ballast and comprising a primary winding connected in series relation with said discharge device, said ballast and said autotransformer, and an electrode heat ing winding inductively coupled to said source to supply heating current to said thermionic electrode, the secondary winding of said step-down transformer being connected to oppose the flow of current in said heating winding upon fiow of current through said primary winding of said stepdown transformer.

2. In combination, a source of current, a gaseous electric discharge device having at least one thermionic electrode and a cooperating electrode, an autotransformer energized from said source and a voltage step-down transformer having a primary winding connected in series relation with an inductive ballast and said autotransformer, a capacitance connected in series relation with the last-mentioned elements, and an electrode heating winding inductively coupled with said source and connected to supply heating current to said thermionic electrode, the secondary of said stepdown transformer being connected to oppose the. flow of current through the primary winding of said step-down transformer upon the flow of current through said device.

3. In combination, a source of current, and a gaseous electric discharge lamp having at least one filamentary electrode and a cooperating e1ectrode, an autotransformer energized from said source and an inductive ballast connected in series relation therewith, means for supplying heating current to said filamentary electrode comprising a winding inductively coupled to said source, a capacitance connected in series relation with said autotransformer and said ballast, and means for reducing the flow of current to said filamentary electrode upon the flow of current between said electrodes without distorting the wave form of the voltage supplied to said device and comprising a voltage step-down transformer having a primary winding connected in series relation with said discharge device and a secondary winding connected in opposition to said heating Winding- EUGENE LEMMERS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,529,344 Coolidge Mar. 10, 1925 1,814,499 Von Wedel July 14, 1931 1,954,784 Braden Apr. 17, 1934 1,980,534 Kirsten Nov. 13, 1934 2,001,567 Case May 14, 1935 2,023,453 Von Wedel Dec. 10, 1935 2,025,471 Osborne Dec. 24, 1935 2,048,203 Spencer July 21, 1936 2,231,584 Lord Feb. 11, 1941 

